Electrolysers are used to perform electrolysis reactions, which either decompose a chemical compound into its elements or produces a new compound, through the action of an electrical current. Electrolysers have a number of electrodes, anodes and cathodes, each separated by a separator such as a membrane. The separator is however optional, as seen in the Chlorate industry, where Sodium Chlorate or Sodium Hypochlorite is produced from the electro-generated chlorine and caustic.
Other examples of electrolysers are fuel cells, where water is electrolysed to produce Hydrogen.
The Chlor-alkali industry also employs electrolysers. The primary products of the electrolysis reaction in such a case are Chlorine, Hydrogen, and Sodium Hydroxide. These compounds are usually in a solution which is commonly called “caustic soda” or simply “caustic”.
Three main electrolysis processes exist and are known as: the membrane process, the diaphragm process and the mercury process. Current trends along with growing environmental concerns are replacing the latter families of processes with the membrane electrolysis process. Chlor-alkali production plants commonly use electrolysers which combine many elementary membrane cells. In a bipolar configuration, for example, the electrolysis process takes place in each elementary cell after applying a current. For many reasons, such as to control the electrolyser's energy consumption and to maximize the production rate, it is desirable to maintain and attempt to improve the electrolyser's efficiency.
While it is possible to measure parameters at the elementary cell level, there is a need for carefully controlling several operational aspects of each elementary cell to determine its respective efficiency and to evaluate its respective damage. There is also a need for determining appropriate maintenance actions on each cell based on an entire electrolyser configuration and efficiency behaviour.